Is anyone collecting ODS data on Steam Turbine Generator Shafts through the TSI BNC's (prox probes)? It seems to me that it would be a fairly simple task - I've been wanting to attempt it however I just can't seem to find the time. Using a CSI 2 Channel 2130, I collect data for ME'Scope models using a fixed (A Channel) and roving (B Channel)accelerometer for normal ODS. I am confused as to how this would be accomplished using the turbine Keyphasor and BNC Outputs. Perhaps the same methodology using a fixed and roving cable to the BNC's would accomplish this. Any ideas or feedback would be greatly appreciated.
Thanks, Mike

Hi Mike,
I've never used prox probes before, but since no one else has helped yet, I'll throw my 2 cents in.
The requirements for ODS data is phase and magnitude. Since you are using a two channel 2130, you can get these without a tach. Just make sure you designate one of the sensors as stationary so a relative phase comparison can be made between the two sensors and you should get a good reading.
The tach pulse only becomes necessary if you are using a single channel box.

This message has been edited. Last edited by: Jon McFadden,

Hi Jon,

Thanks for the feedback. I will try and get an ODS done in the next couple of week. -Mike

Mike - As John stated, what you need for an ODS is amplitude and phase. If you are using a keyphasor, you can get 1X, 2X, etc. If you take the measurements from the proximity probes, you can develop an ODS of the rotor. If you want to do an ODS of the structure, you could still use the keyphasor in lieu of a fixed accelerometer. We had this done a few years ago on the outer "wrapper" of the main generator.

Is your question how to get 1X amplitude and Phase data in the 2130 from the TSI?

Steve

Attached is an example of an Operational Deflection Shape from Bentley prox probe data. The ODS data was measured off of the BNC's on the panel. The machine is a steam turbine generator.

There are two ways to measure this type of data.

1. Use the key phasor as a phase reference and take the measurements using the single channel phase and magnitude function on your analyzer.

2. Tee one of the bearing prox probe channels and use it as a fixed reference while making cross channel phase measurements.

I've done many ODS's from prox probe data. Even more powerful is to do one combining both bearing housing vibration and shaft data.

TG_ODS.zip (71 KB, 78 downloads) Turbine Generator shaft ODS Movie & PDF

Steve, Thanks for the feedback.

Tony, Your turbine/generator shaft(s)ODS is exactly what I am trying to duplicate. In the ME'Scope Software - Measurement Axes (Rectangle, Cylindrical, Spherical, Machine -??). Also, how do you set up the 90 degree (45 Left - 45 Right) to include polarity? I am having difficulty in getting the orbital pattern. Thanks for sharing your animation - nice job. -Mike

Hello Data Dog

In ME'scope...

Create your shaft. It can be a line connecting two points or a cylinder. Either way, keep the coordinates RECTANGULAR.

By default, "Z" will be vertical and "X" or "Y" will be horizontal (depending on your view of the shaft). You can change the software to make "X" or Y" vertical if you wist. I wouldn't bother.

Assign the data from one of the two prox probes on a bearing to the "Z" and the other prox data to "X" or "Y".

If the probes are 45 degrees from vertical, rotate the LOCAL coordinate axes of the point to match the probe direction. Do this in the STRUCTURE window using DRAW / ANIMATION EQUATIONS / EQUATION EDITOR then in the ROTATE section of the MEASUREMENT AXIS tab, rotate on "X" until "Y" and "Z" match the the probes (if you have changed the default "Z" up global axis, you may need to rotate on "Y" or Z" instead of "X").

The orbital patterns are best illustrated by ANIMATING with PERSISTENCE turned on and with DISPLAY POINTS turned on. I recommend doing this to get a screen grab of the shape to put into a report.

This may sound confusing but it is not. It's simple. ME'scope is a wonderful product. I'm willing to help anytime. Just call me or send an email.

Hi Tony,

Thanks for taking time to get me up to speed on ME'Scope utilizing Bently Nevada prox probes. This opens up a whole new world for me. It's amazing to view the orbits through the frequency ranges. I am just experimenting on my BN rotor kit - Looking forward to getting out in the field and doing some actual turbine/generator shafts. Again, Thanks and Happy New Year! - Mike (Data Dog)